Armored conductor structure



March 27, 1945. c. s. GORDON 2,372,323

ARMORED CONDUCTOR STRUCTURE Filed March 14, 1942 INSULATING MATERIALINVENTOR C. S GORDON BY J WW Arrows/E} Patented Mar. 27, 1945 ARMOREDCONDUCTOR STRUCTURE Chester S. Gordon, Boonton, N. J., assignor to BellTelephone Laboratories, Incorporated, New York, N. Y., a corporation ofNew York Application March 14, 1942, Serial No. 434,703 16 Claims. (c1.1v4 1o2) This invention relates to armored conductor structures and moreparticularly to structures of this kind intended for burial directly inthe ground.

It is an object of the invention to provide an armored cable structurewhich is simple to produce, easy to lay and which will provide safeprotection against attacks by burrowing rodents.

, The requirements of a cable of this type capable of answering theseobjects are as follows: The construction should be as light as possibleto reduce cost of materials and tools and to simplify transportation andhandling; the armor-ing should cover the insulated wires as completelyas possible to give adequate protection against attacks and on the otherhand should permit bending of the cable on a comparatively small radiuswithout undue deformation of the armoring, thus permitting the use ofcomparatively small reels; the structure should be non-tangling andshould present a smooth surface to facilitate general handling.

In accordance with the invention a cable structure of this kind isprovided, which includes a single layer of armoring tape with nooverlapping portions. The armoring tape is applied longitudinally of theconductor structure and forms a continuous layer entirely enclosing theinsulated conductor or conductors, except for narrow transverse openingsdisposed at frequent intervals along the cable to permit bending of thearmored structure without appreciable buckling of the tape material. Thelongitudinal seam between tape edges is arranged to provide similarnarrow openings along the seam to permit bending of the structure on acomparatively small radius without buckling of the tape material, thuspreventing exposure to gopher attacks along the seam.

The openings in the body portion of the tape and along the edges arewide enough to prevent crowding of the tape material on the inside ofthe bend without buckling, when the cable is bent, and are narrow enoughto not unduly expose the insulated conductors when widened on theoutside of the bend. The armoring tape furthermore includes smallconnecting portions across the transverse openings for forming acontinuous structure and the connecting portions are crimped to notappreciably reduce the flexibility of the conductor structure impartedby the openings. Other features of the invention will appear from thefollowing detailed description.

The invention will now be described as applied in a practical embodimentof its various features and reference will be made to the accompanyingdrawing in which:

Fig. 1 is a perspective view of an armored cable structure with partsbroken away to more clearly show the construction;

Fig. 2 is a sectional view of the cable structure in Fig. 1;

Fig. 3 is a plan view of the armoring tape used in the structure of Fig.1;

Fig. 4 is a longitudinal edgewise view of the armoring tape; and

Fig. 5 is a view showing the cable structure of Fig. 1 bent over one ofits flat sides on a small radius.

Referring now to Figs. 1 and 2, the preferred cable structure comprisestwo conductors l0 and H placed in parallel relation throughout thestructure and enclosed in insulating material 12 which may form a singlecontinuous body or may comprise two separate bodies of insulation, oneabout each conductor. The tape armoring surrounding the insulation I2comprises two armoring tapes 2| and 22 of suitable material forprotection against gopher attacks. The structure may further includeouter wrappings such as 3| and 32 applied about the armoring tape.

This structure, containing two parallel conductors, thus issubstantially oval-shaped, having two comparatively fiat sides and. tworounded sides or edges. Whereas the armoring tape shown in Figs. 1 and 2is particularly adapted for the oval-shaped structure, it may readily beadapted for cable structures of circular or other cross section. Thearmor-ing tape is shown more in detail in Figs. 3 and 4 in the form itis manufactured before application to the cable structure.

The two tapes 2! and 22 are alike. Thus the tape 2| presents a flatsurface formed of a series of separated transverse strips 21 with shortcrimped or offset connecting portions 24, forming a centralintermittently corrugated body portion 23 with laterally extending edgesections or projectionsZG. The fiat surface is thus interrupted atfrequent intervals by the transverse spaces 25 extending the full widthof the tape and bridged by the connecting portions 24.

The tape material may be iron or steel or any other suitable compositionand may or may not have its surface treated, as by tinning orgalvanization. The material may be non-oxidizing and acid resistant tohave a long life in contact with earth and other substances present inthe ground.

The two tapes are applied longitudinally against the flat sides of thecable and, in the assembling process, are displaced longitudinally sothat a corrugation 25 on one side of the cable will be opposite a fiatbody portion between corrugations on the opposite side of the cable, aswill appear more clearly from Fig. 5. The edge projections 25 are foldedabout the insulated conductors to be return-bent around the roundedsides of the structure, thereby locking the tapes in position. Due tothe fact that the two tapes are relatively shifted the edge projections26 of one tape will be locked in the spaces 25 between the projectionsof the other tape; they thus supplement each other in the protection ofthe insulation. The projections 26 are, however, narrower than thespaces 25 so that, when they are folded in position, a series of narrowtransverse openings 23 will be formed all about the cable, combining toform two opposite helices throughout the length of the armoring.

The openings thus left in the completed armoring should be not more thanA; inch and should preferably average about 1% inch in width. This is topermit laying the cable in the ground with fairly sharp curves or bendswithout unduly exposing the insulation to gopher attacks when theseopenings are widened on the outside of the bend. On the other hand,openings of this width will also prevent crowding of the tape materialon the inside of the bend, when the cable is laid or when it is reeled,so that the armor tape will not be unduly deformed and forced out ofposition, thereby exposing the insulation to gopher attacks.

It has been found that by means of these narrow transverse openings thetape portions formingthe main surface of the armoring are free to shiftslightly along the cable surface either to widen the openings or toclose them up when the cable is bent and that therefore the tendency tobuckle and expose the underlying cable insulation is absent when smallcables are wound on their flat sides on reels as small as 12 inches indiameter.

It has also been found that the introduction of narrow transverseopenings in the tape material. and particularly of the double helicaldistribution of the openings with a comparatively small pitch is greatlyeiiective in reducing the usual stiffness of armored cables of thisgeneral type and in easing the handling thereof both in factory andfield.

In the described structure an undulating seam is formed along each ofthe rounded edges of the cable which. also contributes to theflexibility of the cable. The two tapes are locked safely in positionalong these seams, but, if desired, the outer wrappings 3| and 32 may beapplied over the armoring, which will hold the tape locked around theedges of the conductor structure while the cable is being laid.

As will appear from the drawing, the corrugations are short and straightand thus oiier little resistance to the bending of the cable. As shownin Fig. 5, when the cable is bent the corrugations on the outside of thebend become flattened and those on the inside of the bend close up,thereby preventing the tape from buckling and opening ductor is bent, asin the case of it being wound upon a reel of reasonably small diameter.

The outer wrappings 3i and 32 may be of fibrous material, such as paper,and are helically applied in tape form. The wrappings may be impregnatedor coated with any suitable substance to retard their deterioration.

Cables of the type described above may be used for supplying electriclight and power or for communication purposes. Since they areparticular- 1y adapted for use in rural areas, the distances over whichsuch cables will be used are usually quite considerable. It is thereforeof great importance that the cost of manufacture, and the cost oftransportation and laying be as low as possible.

The self-contained cable structure, described above, is thereforepreferable over cables laid in conduits, since the cable may be plougheddown in a fast continuous process from reels of reasonable size. Thedescribed structure is readily unbent from the reel and laid in sharpcurves without danger of the tape buckling and unduly opening along theseams. With one or two wrappings outside the armoring there is no dangerof tangling or catching as the cable leaves the reel, and the cable maalso readily be manipulated by hand without danger of injury.

The described structurelends itself particularly to fast manufacturing,as compared with cables having helical armor tapes, since thelongitudinal tapes may be applied and locked in position as fast as theinsulated conductor structure can be produced. The two tapes are readilylocked about the conductors and kept at equal speeds to be in accuraterelation on the cable.

Due to the fact that the finished armoring is in effect broken up into alarge number of small shields or strips separated by narrow openings adegree of flexibility may be secured which is at least as high as withhelically applied armor tape.

The absence of buckling of the armorin is 7 especially important ininsuring definite protecstorage, transportation and laying is greatlyfacilitated.

It should be understood that the cable may include more than twoconductors arranged in a single layer and may contain morethan one suchlayer of a plurality of conductors. A single conductor cable, circularor fiat, is also contemplated within the scope of the invention. The twoor more conductors may be twisted together or otherwise intertwined, anda concentric arrangement is also contemplated within the scope of theinvention.

What is claimed is:

1. An elongated structure including insulated conducting means, tapearmoring placed tightly about and longitudinally of said structure andforming single generally continuous layer enveloping said structure andhaving narrow openings extending transversely of said structure, saidopenings being disposed at frequent intervals along said structure andbeing adapted to close up on the inside of the bend, when the structureis bent, thereby substantially preventing buckling of the armoring tape,said tape armoring comprising two supplementary armor ing tapes formingsaid single continuous layer about said structure without overlappingportions and each of said transverse openings extending entirely aroundsaid structure and each of said tapes having oilset connecting portionsacross said openings. 1

2. An elongated structure including insulate conducting means, tapearmoring placed tightly about and longitudinally of said structure andforming a single generally continuous layer enveloping said structureand having narrow openings extending transversely of said structure,said openings being disposed at frequent intervals along said structureand being adapted to close up on the inside of the bend, when thestructure is bent, thereby substantially preventing buckling of thearmoring tape, said tape armoring comprising two supplementary armoringtapes forming said single continuous layer about said structure, eachtape having transverse interruptions in said generally continuoussurface and each interruption being formed partly by one or saidopenings out in the armoring material and partly by a crimp of about thesame width as the opening.

3. An elongated structure including insulated conducting means, tapearmoring placed tightly about and longitudinally of said structure andforming a single generally continuous layer en veloping said structureand having narrow openings extending transversely of said structure,said openings being disposed at frequent intervals along said structureand being adapted to close up on the inside of the bend, when thestructure is bent, thereby substantially preventing buckling of thearmoring tape, said tape armoring comprising two supplementary armoringtapes forming said single continuous layer about said structure and eachhaving ofl'set connecting portions across said opening, and saidtransverse openings being aligned to form a helix about said structure.

4. An elongated structure includin insulated conducting means, tapearmoring placed tightly about and longitudinally oi said structure andforming a single generally continuous layer enveloping said structureand having narrow openings extending transversely of said structure.said openings being disposed at frequent intervals along said structureand being adapted to close up on the inside of the bend, when thestructure is bent, thereby substantially preventing buckling of thearmoring tape, and said transverse openings being aligned to form twoopposite continuous helices about said structure, said tape armoringincluding connecting portions bridged across said openings.

5. An elongated structure including insulated conducting means, tapearmoring placed tightly about and longitudinally of said structure andforming a single generally continuous layer enveloping said structureand having narrow openings extending transversely of said structure,said openings being disposed at frequent intervals along said structureand being adapted to close up on the inside of the bend. when thestructure is bent, thereby substantially preventing buckling of thearmoring tape, said tape armoring including short, crimped connectingportions across said openings arranged in apair of rows on oppositesides of said structure and placed in alternations to permit bending ofthe structure over a small radius without buckling of the tape material.

6. An elongated structure including insulated conducting means, tapearmoring placed tightly about and longitudinally of said structure andforming a single generally continuous layer enveloping said structure,said tape armoring com prising two supplementary armoring tapes formingsaid single continuous layer about said structure with seams havingtheir general direction parallel with the axis of said conductorstructure, each of said tapes having a continuous intermittentlycorrugated body portion and having body extensions projecting from eachside of said continuous body portion, said body extensions from theopposite sides of each seam being relatively displaced longitudinally tobe interspersed along said seam without overlapping of tape material.

7. A long insulated conductor, tape armoring placed tightly about andlongitudinally of said insulated conductor and an outer insulatingsheathing for projection of said armoring, said tape' armoringcomprising two supplementary armoring tapes forming a single generallycontinuous layer enveloping said conductor without overlapping of tapematerial, each of said tapes having a continuous intermittentlycorrugated body portion and having body extensions projecting from eachside of said continuous body portion, said body extensions being spacedapart and return-bent about said conductor and one of said tapes beingdisplaced longitudinally relatively to the other of said tapes so thatsaid body extensions from one tape extend between the separated bodyextensions of the other tape.

8. An elongated insulated conductor, tape armoring placed tightly aboutand longitudinally of said insulated conductor, the tape of saidarmoring forming a single generally continuous layer enveloping saidconductor and being formed of a continuous series of transverseseparated strip portions and including short connecting portionsconnecting adjacent strip portions together into a continuous structurewithout adding appreciable stiffness to said armoring, said stripportions being sulliclently separated to permit bending of the armoredconductor on a small radius without appreciable buckling of the tapematerial in said strip portions, said tape armoring comprising twosupplementary armoring tapes, said connecting portions in each tapebeing disposed in a row substantaially parallel with the conductor axisand on the opposite side of the conductor from the row in the othertape.

9. A long insulated conductor, tape armoring placed tightly about andlongitudinally of said insulated conductor. said tape armoringcomprising two similar tapes forming a single generally continuous layerenveloping said conductor and each having a body portion runninglongitudinally of said conductor and having edge sections extendingtransversely of said conductor from the opposite sides of said bodyportion, said edge sections from each side of said body portion beingspaced apart and. disposed to form a lonitudinal seam together with theedge sections along the opposite side of said seam.

10. A long insulated conductor, tape armoring placed tightly about andlongitudinally of said insulated conductor, said tape armoringcomprising two similar tapes forming a single generally continuous layerenveloping said conductor and each having a body portion runninglongitudinally of said conductor and having edge sections extendingtransversely of said conductor from the opposite sides of said bodyportion, said edge sections from each side of said body portion beingspaced apart and disposed to form a longitudinal seam together with theedge sections along the Opposite side of said seam, said edge sectionsalong opposite sides of the seam between tape edges being relativelydisplaced longitudinally with narrow spaces between them adapted toclose up when the armored conductor is bent.

11. A long, substantially oval-shaped armored conductor structure havingtwo s opposed comparatively fiat sides and two opposed rounded sides andbeing particularly adapted for bending over said flat sides on a smallradius, including a plurality of insulated conductors and tape armoringclosely surrounding said insulated conductors for protection againstattacks by rodents, said tape armoring forming a continuous layerenveloping said plurality of conductors with a seam having its generaldirection parallel with the axis of said conductor structure, the edgesof said tape armoring along said seam forming complementary notches andteeth alternating from opposite sides of said seam without overlappingof the tape mators for protection against attacks by rodents,

said tape armoring forming a continuous layer enveloping said pluralityof conductors with a seam having its general direction parallel with theaXis of said conductor structure, said tape armoring comprising anarmoring tape having a continuous body portion disposed along one ofsaid flat sides and a second similar armoring tape with its body portiondisposed along the opposite flat side, the edges of said armoring tapeforming complementary notches and teeth along said rounded sidesalternating ,from opposite tape edges without overlapping of tapematerial.

13. A long, substantially oval-shaped armored conductor structure havingtwo opposed comparatively fiat sides and two opposed rounded sides andbeing particularly adapted for bending over said flat sides on a smallradius, including a plurality of insulated conductors and tape armoringclosely surrounding said insulated conductors for protection againstattacks by rodents, said tape armoring forming a continuous layerenveloping said plurality of conductors with a seam having its generaldirection parallel with the axis of said conductor structure, said tapearmoring comprising two armoring tapes each having a body portion with aseries of short, spaced transverse corrugations along one of said flatsides and transverse tooth-like extensions from said body portion bentaround said rounded sides without overlapping of tape material.

5 14. A long, substantially oval-shaped armored conductor structurehaving two opposed comparatively flat sides and two opposed roundedsides and being particularly adapted for bending over said fiat sides ona small radius, said structure including a plurality of parallelinsulated conductors, tape armoring closely surrounding said insulatedconductors for protection against attacks by rodents and an outerinsulating sheathing for retaining said armoring in position, said I,armoring comprising two armor tapes placed on opposite flat sides ofsaid structure, each having a lengthwise body portion placed along theflat side, having tooth-like extensions from both sides of said bodyportion return-bent about the rounded sides of said structure and havingshort transverse corrugations disposed between said extensions, one ofsaid tapes being displaced longitudinally relatively to the other tapeto prevent overlapping of tape material in said return-bent extensionsand to place said corrugations in alternations on the opposite fiatsides of said struc ture.

15. An armored cable including an insulated conductor and twosupplementary armoring tapes each comprising a series of substantiallydiamond-shaped portions and crimped connecting pieces between saidportions, said two tapes being applied on the opposite sides of thecable and being return-bent about said cable without overlapping of tapematerial.

16. An armoring tape for a cable comprising a series of substantiallydiamond-shaped portions and crimped connecting pieces between said por-

